Kelvin_Stop_Scaring_Party@tg says to 電訊台
i = len(s) j = len(reverse_s) solve(s, reverse_s, i, j): if(i == 0 || j == 0) return 0 if(s[i] == reverse_s[j]) return solve(x, y, i - 1, j - 1) + 1 else return max(solve(x, y, i - 1), solve(x, y, i , j - 1))